Dual lamp illumination system
A dual lamp illumination system adapted for a projection display system. The dual lamp illumination system includes a first illumination module and a second illumination module, a beam deflecting unit, and a light homogenizer. The first and the second illumination modules each includes a light source, and an elliptically-shaped housing having an interior reflective coating. The light sources each generates an optical beam comprising converging optical rays such that optical beams each has an angular distribution range of [−P, +Q] degrees, where P and Q are preferably 30. The beam deflecting unit reflects at least one of the optical beams from the first and the second illumination module and couples the optical beams to form a multiplexed beam. The light homogenizer is then for homogenizing the multiplexed beam. The invention achieves throughput of 1.5×–1.7× higher gain than single lamp illumination systems useful particularly in a projection display system.
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1. Field of the Invention
The invention relates in general to an illumination systems, and more particularly to a dual lamp illumination system.
2. Description of the Related Art
Projection systems are widely used in various applications. In a conventional projection system, an arc lamp is used for generating an optical beam. The optical beam, through the color wheel, is then filtered into red, green and blue components. The filtered optical beam is in turn directed towards a light pipe, for modifying the distribution of the optical beam and making the light intensity distribution more uniform.
The optical beam from the light pipe is then relayed by relay optics, such as condensing lens and mirrors, to a digital micro-mirror device (DMD). The DMD includes a number of micro mirrors that can be arranged to either selectively reflect the optical beam towards projection lens to produce image light, or block the optical beam from getting through the projection lens. The optical beam from the projection lens is then projected onto the display screen, thereby displaying an image.
However, the arc lamps used by the conventional projection system often cannot be scaled up to high enough power levels. That is, low lumens level causes the image projected on display screen to appear dark. Due to such inherent drawbacks, methods for increasing power levels have thus been an important topic.
SUMMARY OF THE INVENTIONIt is therefore an object of the invention to provide a dual lamp illumination system, adapted for a projection display system, that has high throughput. Therefore, the display screen can receive higher power level to display brighter image.
The invention achieves the above-identified object by providing a dual lamp illumination system adapted for a projection display system. The dual lamp illumination system includes a first illumination module and a second illumination module, a beam deflecting unit, and a light homogenizer. The first and the second illumination modules each includes a light source, and an elliptically-shaped housing having an interior reflective coating. The light sources each generates an optical beam comprising converging optical rays such that optical beams each has an angular distribution range of [−P, +Q] degrees, where P and Q are preferably 30. The beam deflecting unit is positioned on the paths of the optical beams of the first illumination module and the second illumination module. The beam deflecting unit reflects at least one of the optical beams from the first illumination module and the second illumination module and couples the optical beams from the first illumination module and the second illumination module to form a multiplexed beam. The light homogenizer is then for homogenizing the multiplexed beam.
The first illumination module and the second illumination module each further includes a beam expander, for reducing the angular distribution range of the optical beams generated by the light sources of the first illumination module and the second illumination module to substantially no less than [−P/3, Q/3] degrees and substantially no greater than [−2P/3, 2Q/3] degrees. The light sources of the first illumination module and the second illumination module are preferably implemented with arc lamps and back mirror lamps. The system further includes a beam condenser, for receiving the multiplexed beam from the beam deflecting unit before the multiplexed beam enters the light homogenizer.
Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.
Embodiment 1
The light homogenizer 130, preferably a rectangular light tunnel, then homogenizes the multiplexed beam MB, and adjusts the light intensity distribution of the multiplexed beam. That is, due to the nature of the housings 112(1) and 112(2) of the illumination modules being elliptically shaped, the light intensity distributions of the optical beams OB1 and OB2 thus generated are circular. Hence, the light homogenizer 130, in addition to homogenizing optical beams, is used to convert the circular light intensity distribution into a rectangular light intensity distribution, such that when the dual illumination system 100 is adapted in a projection system, the optical beams OB1 and OB2 produced by light sources 114(1) and 114(2) can ultimately be relayed onto a panel of the DMD, which is often rectangular in shape.
The light sources 114(1) and 114(2) of the first and second illumination modules 110(1) and 110(2) are implemented with back mirror lamps, for example. The back mirror lamp is an arc lamp with reflecting coating on front side of a burner of the arc lamp. The angular distribution of the back mirror lamp is about 15 degree. The first and second illumination modules 110(1) and 110(2) using back mirror lamps generally produce optical beams OB1 and OB2 that have angular distributions [−15, +15] degree. In this case, the value of P and Q are both substantially equal to 15.
Besides, the angular distribution of the optical beams OB1 and OB2 generated by the first and second illumination modules 110(1) and 110(2) are not limited to [−15, +15] degree. The object of the embodiment can be still achieved when the angular distribution of the optical beams OB1 and OB2 generated by the first and second illumination modules 110(1) and 110(2) both have a range of no less than [−10, +10] degree and no greater than [−20, +20] degree.
The beam deflecting unit 120 is a prism, for example. Referring again to
Referring to
Thus, as demonstrated by the simulation results of
The modulated beam MB″ focused on the display screen 570 is referred to as being at the far field.
Embodiment Two
Referring to
Embodiment Three
Referring to
Preferably, the angular distribution of the optical beams OB1 and OB2 generated by first and second illumination modules 810(1) and 810(2) each has a range of no less than [−10,+10] and no greater than [−20,+20].
Embodiment Four
Referring to
Thus, as shown, by utilizing two illumination modules to generate optical beams that couple to form a multiplexed beam that is then relayed onto the panel of the DMD, the resulting throughput has a gain of 1.5 to 1.7 times as compared to single lamp systems. Additionally, by utilizing condenser lenses and expander lenses, the embodiments of the invention effectively prevents the effects of overfill on DMD.
While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Claims
1. A dual lamp illumination system, adapted for a projection display system, comprising:
- a first illumination module and a second illumination module, each comprising a light source, and an elliptically-shaped housing having an interior reflective coating, the light sources each generating an optical beam comprising converging optical rays, the optical beams each having an angular distribution range of [−P, +Q] degrees, P, Q being real numbers, wherein each of the first illumination module and the second illumination module further comprises a beam expander, for reducing the angular distribution range of the optical beams generated by the light sources of the first illumination module and the second illumination module;
- a beam deflecting unit, positioned on the paths of the optical beams of the first illumination module and the second illumination module, wherein the first illumination module and the second illumination module face different sides of the beam deflecting unit, the beam deflecting unit reflects at least one of the optical beams from the first illumination module and the second illumination module and couples the optical beams from the first illumination module and the second illumination module to form a multiplexed beam which converges at a focal point; and
- a light homogenizer, for homogenizing the multiplexed beam.
2. The system according to claim 1, wherein P and Q are substantially equal to 30, the beam expander reduces the angular distribution range of the optical beams generated by the light sources of the first illumination module and the second illumination module to substantially no less than [−P/3, Q/3] degrees and substantially no greater than [−2P/3, 2Q/3] degrees.
3. The system according to claim 2, wherein the light sources of the first illumination module and the second illumination module are arc lamps.
4. The system according to claim 1, wherein P and Q are substantially no less than 10 and substantially no greater than 20.
5. The system according to claim 4, wherein the light sources of the first illumination module and the second illumination module are back mirror lamps.
6. The system according to claim 5, where P and Q are substantially equal to 15.
7. The system according to claim 1, wherein the a focal point is on a focal plane FP at an entrance of the light homogenizer.
8. The system according to claim 7, wherein the focal point is located at the entrance of the light homogemzer.
9. The system according to claim 1, wherein the beam deflecting unit comprises a prism which comprises a first reflective surface and a second reflective surface, the first reflective surface and the second reflective surface of the prism face the first illumination module and the second illumination module respectively, for reflecting the optical beams from the first illumination module and the second illumination module toward the homogenizer to form the multiplexed beam.
10. The system according to claim 9, wherein the first reflective surface and the second reflective surface intersect in a line to form an apex angle, the apex angle is substantially no less than 90 degrees and substantially no greater than 110 degrees, the angular distribution range of the optical beams from the first illumination module and the second illumination module are both substantially no less than 10 degrees and substantially no greater than 20 degrees.
11. The system according to claim 10, wherein the light homogenizer is a tapered rectangular tunnel, the length, along the direction perpendicular to the directions of the optical beams and the multiplexed beam, of the entrance of the tapered rectangular tunnel is substantially twice of the length of the exit of the tapered rectangular tunnel, and the width of the exit of the tapered rectangular tunnel is substantially the same as the width of the entrance of the tapered rectangular tunnel.
12. The system according to claim 1, wherein the beam deflecting unit comprises a total internal reflection (TIR) prism, the propagating directions of the optical beams from the first illumination module and the second illumination module before the optical beams entering the TIIR prism are substantially perpendicular with respect to each other, a surface of the TIR prism total internally reflects the optical beam from the first illumination module to cause the reflected optical beam to propagate towards the light homogenizer, and the optical beam from the second illumination module passes through the surface and then propagate towards the light homogenizer.
13. The system according to claim 12, wherein the system further comprises a beam condenser, for receiving the multiplexed beam from the beam deflecting unit before the multiplexed beam enters the light homogenizer.
14. The system according to claim 13, wherein the light homogenizer is a rectangular light tunnel.
15. The system according to claim 12, wherein the first illumination module and the second illumination module face a first side and a second side of the beam deflecting unit respectively, the at least one optical beam from the first illumination module is perpendicular to the first side and at least one optical beam from the second illumination module is perpendicular to the second side.
16. The system according to claim 12, wherein the propagating directions of the optical beams from the first illumination module and the second illumination module before the optical beams entering the TIR prism are substantially perpendicular with respect to each other.
17. The system according to claim 12, wherein the TIR prism has a first angle of about 99.25 degrees and a second angle of about 32 degrees.
18. The system according to claim 17, wherein the TIR prism has a third side adjacent to the first side and opposite to the second side, and the third side is longer than the first side.
19. The system according to claim 18, wherein the first angle is included between the third side and the surface.
20. The system according to claim 18, wherein the second angle is included between the third side and the first side.
Type: Grant
Filed: Jan 6, 2005
Date of Patent: May 29, 2007
Patent Publication Number: 20060146296
Assignee: Benq Corporation (Taoyuan Shien)
Inventor: Ming-Kuen Lin (Taisi Township, Yunlin County)
Primary Examiner: Rodney Fuller
Attorney: Rabin & Berdo, P.C.
Application Number: 11/029,625
International Classification: G03B 21/26 (20060101); G33B 21/28 (20060101);